A variety of instruments are used in surgery, said instruments being operated within a surgical system and, in doing so, being powered by a surgical apparatus. Such surgical instruments are, for example, RF surgical instruments provided with electrodes or applicators used for conveying media, said media being different from electric current, to biological tissue at an active site of the operating field. Such active media can be e.g., water, cryomedia or the like. A cable/conduit for the electric current or the other active medium is used between the supplying surgical apparatus and the respectively used instrument.
Frequently, different instruments and accessory parts are provided on a surgical apparatus and driven by said apparatus for operation. The instruments may be of different types. For example, so-called monopolar handles that may be configured as an electric scalpel, a coagulation instrument, a resection instrument or the like, are used. For this, exchangeable electrodes are also frequently used. Bipolar instruments such as e.g., clamps, gripping forceps and the like are also used for coagulating, severing blood vessels or for similar purposes. As a rule, these different instruments require individually specific operating modes for electric activation.
The goal is to ensure that the instrument is not operated in an unsuitable mode. To this end, international publication WO 2009/074329 A2 suggests that the instrument be associated with an RFID transponder that communicates with an instrument antenna. Inside the surgical apparatus, there is an emitter/receiver unit that communicates with the RFID transponder and, in this manner, identifies the connected instrument. Furthermore, this publication suggests the transmission of commands from switches to the surgical apparatus via the RFID transponder, in which case the switches are arranged on the instrument. The instrument may also comprise sensors outputting signals that are being processed and output to the surgical apparatus via the RFID transponder. In doing so, the RFID transponder is arranged as closely as possible to the apparatus, preferably in the plug of the surgical apparatus that is to be connected, or in the connecting cable itself.
Furthermore, U.S. Pat. No. 7,503,917 B2 discloses an instrument that comprises several control switches. These are connected with the surgical apparatus via signal cables. The control switches short-circuit individual resistors of a cascaded voltage divider and thus emit a characteristic voltage signal to the signal cables; said voltage signal being used by the surgical apparatus to detect the switch actuation assigning it to specific switches.
The electrical environment in the operating room is at times subject to very strong interferences. Radio-frequency voltages and currents in the immediate vicinity of the surgical apparatus, surgical instrument and connecting cable lead to high interference field strengths that can negatively affect the signal transmission.
U.S. Pat. No. 7,479,140 B2 also uses analog signal cables for the transmission of switch commands from the surgical instrument to the apparatus, said cables being used to connect diverse characteristic resistors with the surgical apparatus.
Furthermore, German publication DE 10 2005 044 918 A1 discloses a system for the contactless identification and communication between a surgical apparatus and a connected instrument. Again, a transponder that is arranged in the instrument plug of the surgical instrument is used. The associated apparatus socket comprises a reading unit that communicates with the transponder. Many adjustments of the surgical apparatus need to be made directly on the apparatus; the surgeon has only a few adjustment options on the instrument.